| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a control method for smoothly restarting an AC motor in a free running state. <P>SOLUTION: An apparatus for controlling the AC motor has an output voltage arithmetic circuit 9 which calculates the amplitude and phase of an output voltage from a voltage command Vqref outputted from an exciting current control circuit 6, a torque current control circuit 5, and a V/f converter circuit 8. The control method includes steps of: adding a phase angle outputted from a phase angle arithmetic circuit to the amplitude and phase of a voltage outputted from the output voltage arithmetic circuit, and deciding switching of a power converter 1 not having a speed detector circuit nor a voltage detection circuit. Further, when the AC motor in a free running state is started, an output frequency is lowered if a torque current detection value is positive; and the output frequency is raised if the torque current detection value is negative, so that the output frequency is adjusted so as to approximate the torque current detection value to zero. <P>COPYRIGHT: (C)2008,JPO&INPIT |
